"The size of the final order book and the spread of investor interest across the globe demonstrate the appetite for Irish sovereign debt and Ireland's ability to fund its needs in the private debt markets," the agency said in a statement.

It said that, despite the large order book, it had restricted the size of today's deal to €3.75 billion in order to accommodate bond auctions in its funding programme for the remainder of the year.

"It is clear from the very significant demand we saw today that international and domestic investors recognise the enormous progress Ireland has made. Today's transaction is a real success that cements Ireland's return to the international debt markets and provides a strong platform for bond auctions in 2014", commented the NTMA's chief executive John Corrigan.

In reaction to today's auction, Irish bond yields fell to eight-year lows. Analysts said the deal was final confirmation that investors trusted Ireland to recover unaided from its property market crash, having just come through an €85 billion EU/IMF bailout programme undertaken in 2010.

Irish 10-year bond yields fell by nine 9 basis points to 3.27%, their lowest in eight years, according to Reuters historical data. They had peaked at over 15% in 2011.

Some analysts said the deal offered proof of increased market access and should be supportive for Ireland's credit ratings. Moody's, the only big agency to rate Ireland below investment grade, is due to review its ratings on January 17.

Minister for Finance Michael Noonan welcomed the bond sales, saying that the yield “illustrates the strength of Ireland’s international reputation” and brought the country’s borrowing rates closer to the region’s strongest economies.

He said that the level of demand for the sale had shown that the Government’s decision to exit the bailout without a precautionary credit line had helped to give investors confidence in the country.

Today's sale was the country's first bond issue since March 2013, when it sold €5 billion in a 10-year transaction. It is being seen as a bellwether both for investor confidence in Ireland's ability to go it alone after it successfully exited its bailout in December, and market appetite for the debt of other countries in Europe's periphery.

The country is already funded into 2015. But the NTMA had wanted to resume regular bond auctions to demonstrate the country had returned to "business as usual" and to insure itself against possible future market turbulence.

Analysts said evidence that a euro zone country was able to successfully exit its bailout could increase confidence that Portugal could follow in Ireland's footsteps when its aid deal comes to an end later in 2014.

Portuguese bonds have outperformed other euro zone debt this year, with 10-year yields falling around half a point to 5.53% since the end of 2013 as an improving global growth outlook increased appetite for riskier assets.